There have been proposed a variety of liquid jet recording systems (bubble jet recording systems in other words). Among such liquid jet recording systems, the public attention has been focused on those liquid jet recording systems disclosed, for example, in U.S. Pat. Nos. 4,723,129 and 4,740,796 in recent years. Such liquid jet recording systems are of the type that a recording liquid (typically, ink) is discharged utilizing thermal energy and recording is performed with the recording liquid (ink) discharged. There are advantages for these liquid jet recording systems that recording of a high quality image with a high density and a high resolution can be performed at a high speed and it is easy to attain color recording and miniaturization. A typical embodiment of the recording apparatus in which such liquid jet recording system is employed comprises an ejection outlet for ejecting recording liquid (ink), a liquid pathway in communication with said ejection outlet and having, as part of its constituent, a heat acting portion at which thermal energy, which is utilized for ejecting the liquid (ink) from the ejection outlet, is effected to the liquid, and an electrothermal converting body which is disposed to correspond to the liquid pathway and which serves to generate the thermal energy to be utilized for ejecting the liquid (ink).
As for the constitution of the recording head to be used in such liquid jet recording system as above described, there are known two types in general classification; a first type having ink pathways in communication with a common liquid chamber which comprises a base member provided with heat generating elements, partition walls made of a photosensitive resin and a top plate, and a second type having ink pathways in communication with a common liquid chamber, formed by providing a member to be a top plate provided with grooves to provide the ink pathways and the common liquid chamber which were formed by means of etching technique and a base member provided with heat generating elements and laminating the former on the latter to establish the ink pathway and the common liquid chamber.
There is known a head cartridge having the configuration of the above-mentioned second type in which the ink jet head is connected to an ink supply tank. Specifically, an example of such head cartridge is of the constitution shown in FIGS. 1 and 2. The head cartridge shown in FIGS. 1 and 2 is detachably set to a recording apparatus. The ink jet recording head in this case further comprises an ejection board provided with ink ejection outlets which is integrated to the foregoing grooved member by means of injection molding technique.
FIG. 1 is a schematic exploded view of the head cartridge. In FIG. 1, "IJU" stands for a unit of the system for generating thermal energy depending upon a electric signal applied to cause film boiling at ink, thereby ejecting ink. Reference numeral 100 stands for a heater board comprising a plurality of electrothermal converting bodies serving to generate said thermal energy which are linearly arranged on a Si base member and electric wiring made of Al, etc. serving to supply electric power to the electrothermal converting bodies. Reference numeral 200 stands for a wiring board containing wirings corresponding to the wirings of the heater board 100 and a plurality of pads 201 situated at the portion behind said wirings and which serve to receive electric signals from the main body of the apparatus. Reference numeral 1300 stands for a top plate provided with partition walls constituting ink pathways corresponding to ink ejection outlets and a common liquid chamber. The top plate 1300 is integrally provided with a socket 1500 and an orifice plate 400. The socket 1500 serves to receive ink supplied from an ink container and introduce the ink into the common ink chamber. The orifice plate 400 is provided with a plurality of ejection outlets. The partition walls disposed at the top plate 1300 are integrally formed with the top plate using an appropriate resin material such as polysulfone.
Reference numeral 300 stands for a support member made of a metal for example. The support member 300 is a structural constituent of the recording head unit and it serves to support the wiring board 200 through the rear face thereof. Reference numeral 500 stands for a pressure bar plate spring in the M-like form. The pressure bar plate spring 500 serves to press the portion of the top plate 1300 corresponding to the common liquid chamber by the central portion thereof while pressing the portion of the top plate 1300 corresponding to the ink pathways through the linear contact by a drooped portion 501 of the pressure bar plate spring. The pressure bar plate spring 500 has leg portions which are contacted to the rear face of the support member 300 while penetrating through openings 3121 of the support member, wherein the heater board 100 and the top plate 1300 are made such that they are pinched between the support member 300 and the pressure bar plate spring 500. Thus, the heater board 100 and the top plate 1300 are secured to be pressure contacted to the support member 300 by way of an urging force caused by the pressure bar plate spring 500 and the drooped portion 501. The support member 300 contains a pair of positioning openings 312 corresponding to a pair of positioning protrusions 1012 mounted at the ink container and another pair of positioning openings 1900 corresponding to a pair of positioning and thermally fuse-fixing protrusions 1800 mounted also at the ink container. At the rear face of the support member 300, there are disposed a pair of positioning protrusions 2500 and 2600 for the positioning relative to the carriage on the side of the main apparatus body. The support member 300 further contains an opening 320 which permits an ink supply pipe serving to supply ink from the ink container to penetrate therethrough. The wiring board 200 is fixed to the support member 300 by means of an adhesive or the like.
The support member 300 is provided with a pair of recessions 2400 respectively positioned near the positioning protrusion 2500 or 2600. And, as shown in FIG. 2, the assembled head cartridge IJC has a head projected portion having three sides provided with a plurality of parallel and continuous grooves 3000 and 3001. The recessions 2400 are located at extensions of the grooves at the top and bottom sides to prevent the ink or foreign matters such as dust moving along the grooves from reaching the positioning protrusions 2500 and 2600. Reference numeral 800 stands for a covering member provided with the parallel grooves 3000. The covering member 800 constitutes an outer casing of the head cartridge IJC and cooperates with the ink container to define a space for accommodating the recording head unit IJU. Reference numeral 600 stands for a ink supply passage member provided with the parallel grooves 3001. The ink supply passage member 600 has an ink conduit 1600 in communication with an ink supply pipe 2200 and cantilevered on the side of the ink supply pipe 2200. In order to assure the capillary action with the ink supply pipe 2200 at the fixed portion with the ink conduit 1600, a sealing pin 602 is provided.
Reference numeral 601 stands for a gasket to seal the connecting portion between the ink container and the ink supply pipe 2200. Numeral reference 700 stands for a filter disposed at the container side end of the ink supply pipe 2200. The ink supply passage member is molded, and therefore, it is produced at a reduced cost with a high positional accuracy. In addition, the cantilevered structure of the ink conduit 1600 assures the press-contact between the ink conduit 1600 and ink inlet 1500 of the top plate 1300 even if the ink supply passage member 600 is mass-produced. In this embodiment, a sealing bonding agent is flown from the side of the ink supply passage member under the press-contact state.
The ink supply passage member 600 may be easily fixed to the support member 300 by inserting and penetrating backside pins (not shown) of the ink supply passage member 600 through openings 1901 and 1902 of the support member 300 and by heat-fusing the portion where the pins are projected through the backside of the support member 300. The slight projected portions in this case are accommodated in recessions (not shown) in the recording head unit IJU mounting side face of the ink container and therefore, the unit IJU can be correctly positioned.
The ink container comprises a cartridge main body 1000, an ink absorbing material 900 and a cover member 1100. The ink absorbing material 900 is inserted into the cartridge main body 1000 from the side opposite from the unit IJU mounting side and thereafter, the cover member 1100 seals the cartridge main body. The ink absorbing material 900 is thus disposed in the cartridge main body 1000. Reference numeral 1200 stands for an ink supply port which serves to supply ink to the unit IJU comprising the foregoing parts 100-600. It also serves as an ink injection inlet to permit initial ink supply to the absorbing material 900 before the unit IJU is mounted to the portion 1010 of the cartridge main body 1000.
In this embodiment, the portions through which ink can be injected into the ink container are air vent port 1401 and the ink supply port 1200. There are disposed ribs 2300 on the inside face of the cartridge main body and other ribs 2500 and 2501 on the inside face of the cover member 1100. These ribs are effective to provide within the ink container an air existing region extending continuously from the side of the air vent port 1401 to the corner portion of the cartridge main body which is most remote from the ink supply port 1200. By this, a good supply of ink from the ink absorbing material is ensured. Therefore, in order to perform relatively good and uniform injection of the ink, it is important to supply the ink through the ink supply port 1200. This ink supply method is practically effective. The number of the ribs 2300 in this embodiment is four (in FIG. 1, the two ribs on the upper face are shown). The ribs 2300 extend parallel to a movement direction of the carriage adjacent to the rear side of the cartridge main body 1000, by which the absorbing material is prevented from being closely contacted to the inner surface of the rear side of the cartridge main body 1000. The ribs 2301 and 2302 are disposed on the inside face of the cover member 1100 at an extended position in the direction of an extension of the ribs 2300, however, as contrasted to the ribs 2300, they are designed to be divided ribs. By this, the air existing space is made larger than the former. The ribs 2301 and 2302 are distributed on the entire area of the cover member 1100, and the area thereof is not more than one half of the total area. By these ribs, the ink in the corner region of the ink absorbing material 900 which is most remote from the ink supply port 1200 can be stably and assuredly supplied to the side of the ink supply port by capillary action. Reference numeral 1401 stands for an air vent port disposed at the cover member for communication between the inside of the ink container with the outside air. Reference numeral 1400 stands for a water repellent material arranged in the inside of the air vent port 1401. The water repellent material 1400 serves to prevent the ink from leaking outside through the air vent port 1400.
The ink accommodating space of the ink container is in a substantially rectangular form, and the long side thereof faces in the direction of carriage movement, and therefore, the foregoing rib arrangements are particularly effective. When the long side extends along the movement direction of the carriage, or when the ink accommodating space is in the form of a cube, the ribs are desirably disposed on the entire surface of the cover member 1100 to thereby stabilize the ink supply from the ink absorbing member 900.
The ink container is covered by the cover member 800 after the unit IJU is mounted thereto. Then, the unit IJU is enclosed therearound except for the bottom thereof. However, the head cartridge is mounted to the carriage on the side of the main body, where the bottom opening thereof comes close to the carriage to thereby form a space substantially enclosed on all sides. Because of this, the heat generation from the recording head IJH in the enclosed space distributes uniformly within the enclosed space to maintain the temperature of the enclosed space at a uniform value. However, there is an occasion that the temperature slightly increases when the recording head IJH is continuously operated over a long period of time. In order to avoid occurrence of such temperature rise, there is disposed a slit 1700 having a width smaller than the enclosed space, by which the spontaneous heat radiation is enhanced to prevent the temperature rise, while the uniform temperature distribution of the entire of the unit IJU is not influenced by the ambient conditions.
After being assembled as the head cartridge IJC as shown in FIG. 2, ink is supplied from the ink supply port 1200 of the ink container to the ink conduit 1600 in the ink supply passage member 600 through the opening 320 of the support member 300 and a supply pipe 2200 arranged while penetrating through an inlet disposed at the rear side of the chamber of the ink supply passage member 600. After passing therein, the ink is supplied to the common chamber through the ink inlet port 1500 of the top plate 1300. The connecting portions of the supply pipe and the conduit are provided with a packing of silicon rubber, butyl rubber or the like to hermetically seal them, whereby the ink supply passage is assured.
In this embodiment, the top plate 1300 is made of a resin excelling in resistance to the ink, such as polysulfone, polyether sulfone, polyphenylene oxide, polypropylene, etc. It is integrally molded in a mold together with an orifice plate portion 400.
As above described, the integrally molded part comprises the ink supply passage member 600, the top plate-orifice plate integral and the ink container body. Therefore, the accuracy in the assembling is improved, and is extremely effective in the mass-production. The number of parts is smaller than that in the prior art, so that the good performance is assured.